Things haven't gone too well for subscription MMOs this week. On Tuesday, EA announced that it's turning Star Wars: The Old Republic into a free to play game to combat its declining user numbers, and today Activision Blizzard revealed that World of Warcraft lost more than one million subscribers in just three months.

As part of the publisher's quarterly earnings report, Activision Blizzard revealed that World of Warcraft had 9.1 million subscribers as of June 30, 2011. That's an impressive figure, to be sure, but it's soured a bit by the fact that the game boasted as many as 10.2 million subscribers in March.

World of Warcraft has been leaking subscribers for some time now, but this drop is the game's steepest in recent memory. Over the past several quarters, the game's player count has remained relatively stable, hoveringaround that 10.2 million mark.

Activision Blizzard hopes to stop, and perhaps reverse those declining numbers later this year, when it launches World of Warcraft's latest expansion: Mists of Pandaria. Typically, these content updates have helped breathe new life into the seven year old MMO, so this upcoming release should help the game hold onto its players for at least a little bit longer.

Much like World of Warcraft, EA and BioWare's Star Wars: The Old Republic has also seen its subscriber numbers drop off over the last few months, and the game hopes to address these issues in November when adopts a brand new free to play business model. Of course, The Old Republic's situation is particularly rough compared to World of Warcraft, as it currently has fewer than one million subscribers.

For now, at least, World of Warcraft is holding strong as one of the few remaining subscription MMOs, but with it and other games struggling to hold onto their audience, it's hard to say how long that'll last.

Looking at Activision Blizzard's overall performance over the last quarter, the company saw a few notable declines, but still managed to exceed overall expectations. For the three months ended June 30, the company pulled in revenues of $1.08 billion, which was down from $1.14 billion year over year, but exceeded the average analyst expectation of $834.8 million. Profits, meanwhile, hit $185 million, down from $335 million during this period last year.

[Update: During a Gamasutra-attended investor conference call, Blizzard president Mike Morhaime pointed out that most of the players who dropped out of World of Warcraft this quarter were from Eastern territories. He added that he believes a number of players are "taking a break" from World of Warcraft to play the recently-launched Diablo III.]